The present invention relates to intake and exhaust valves control of an internal combustion engine.
Various attemps have been made to improve performance of an internal combustion engine.
Japanese Patent Application First Publication No. 59-103910 discloses an apparatus for operating intake and exhaust valves of an internal combustion engine, which is adapted to increase a valve overlap by controlling opening and closing timings of the intake valve during an engine operation under cold condition.
Japanese Patent Application First Publication No. 1-159431 discloses an apparatus for operating intake and exhaust valves of an internal combustion engine, which is adapted to retard an opening timing of the exhaust valve after a bottom dead center of the piston exhaust stroke during an engine operation under cold condition.
An object of the present invention is to achieve a reduction in hydrocarbon (HC) emission during the engine operation under cold condition.